﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace FwProject
{
    public class FontHelper
    {
        /// <summary>
        /// 在指定的字符串列表CnStr中检索符合拼音索引字符串
        /// </summary>
        /// <param name="CnStr">汉字字符串</param>
        /// <returns>相对应的汉语拼音首字母串</returns>
        public static string GetSpellCode(string CnStr)
        {

            string strTemp = "";

            int iLen = CnStr.Length;


            //for (i = 0; i <= iLen - 1; i++)
            //{

            //    strTemp += GetCharSpellCode(CnStr.Substring(i, 1));
            //    break;
            //}
            strTemp= GetCharSpellCode(CnStr.Substring(0, 1));

            return strTemp;

        }

        /// <summary>
        /// 得到一个汉字的拼音第一个字母，如果是一个英文字母则直接返回大写字母
        /// </summary>
        /// <param name="CnChar">单个汉字</param>
        /// <returns>单个大写字母</returns>
        private static string GetCharSpellCode(string CnChar)
        {
            long iCnChar;
            byte[] ZW = System.Text.Encoding.GetEncoding("gb2312").GetBytes(CnChar);

          
            //如果是字母，则直接返回
            if (ZW.Length == 1)
                return CnChar.ToUpper();
            else
            {
                int i1 = (short)(ZW[0]);
                int i2 = (short)(ZW[1]);
                iCnChar = i1 * 256 + i2;
            }

            // iCnChar match the constant
            if ((iCnChar >= 45217) && (iCnChar <= 45252))
                return "A";
            else if ((iCnChar >= 45253) && (iCnChar <= 45760))
                return "B";
            else if ((iCnChar >= 45761) && (iCnChar <= 46317))
                return "C";
            else if ((iCnChar >= 46318) && (iCnChar <= 46825))
                return "D";
            else if ((iCnChar >= 46826) && (iCnChar <= 47009))
                return "E";
            else if ((iCnChar >= 47010) && (iCnChar <= 47296))
                return "F";
            else if ((iCnChar >= 47297) && (iCnChar <= 47613))
                return "G";
            else if ((iCnChar >= 47614) && (iCnChar <= 48118))
                return "H";
            else if ((iCnChar >= 48119) && (iCnChar <= 49061))
                return "J";
            else if ((iCnChar >= 49062) && (iCnChar <= 49323))
                return "K";
            else if ((iCnChar >= 49324) && (iCnChar <= 49895))
                return "L";
            else if ((iCnChar >= 49896) && (iCnChar <= 50370))
                return "M";
            else if ((iCnChar >= 50371) && (iCnChar <= 50613))
                return "N";
            else if ((iCnChar >= 50614) && (iCnChar <= 50621))
                return "O";
            else if ((iCnChar >= 50622) && (iCnChar <= 50905))
                return "P";
            else if ((iCnChar >= 50906) && (iCnChar <= 51386))
                return "Q";
            else if ((iCnChar >= 51387) && (iCnChar <= 51445))
                return "R";
            else if ((iCnChar >= 51446) && (iCnChar <= 52217))
                return "S";
            else if ((iCnChar >= 52218) && (iCnChar <= 52697))
                return "T";
            else if ((iCnChar >= 52698) && (iCnChar <= 52979))
                return "W";
            else if ((iCnChar >= 52980) && (iCnChar <= 53640))
                return "X";
            else if ((iCnChar >= 53689) && (iCnChar <= 54480))
                return "Y";
            else if ((iCnChar >= 54481) && (iCnChar <= 55289))
                return "Z";
            else
                return ("?");
        }


        /// <summary>
        /// 截取字符长度
        /// </summary>
        /// <param name="str">被截取的字符串</param>
        /// <param name="len">所截取的长度</param>
        /// <returns>子字符串</returns>
        public static string CutString(string str, int len)
        {
            if (str == null || str.Length == 0 || len <= 0)
            {
                return string.Empty;
            }

            int l = str.Length;


            #region 计算长度
            int clen = 0;
            while (clen < len && clen < l)
            {
                //每遇到一个中文，则将目标长度减一。
                if ((int)str[clen] > 128) { len--; }
                clen++;
            }
            #endregion

            if (clen < l)
            {
                return str.Substring(0, clen) + "...";
            }
            else
            {
                return str;
            }
        }


    }
}
